Surface Deformation of Expansive Soil at Ankang Airport, China, Revealed by InSAR Observations

Round 1

Reviewer 1 Report

This manuscript presents a study about using InSAR to monitor displacements in an airport, together with fill depth and rainfall data. I think the study is interesting; however, several improvements in the text and figures are required:

• Line 165: "vertical accuracy" instead of "vertical resolution";

• Equation (1): the ‘}’ is missing and the ‘<A(p)’ on the right is not needed. Please revise.

• Line 664: Reference 31 is incomplete.

• Equation (3): ‘}’ is missing.

• Figure 4: How can SLCs result from co-registered SAR images? Please verify if the figure is correct.

• Line 323: L1 and L2 are are represented in Figure 9 and not in Figure 10(a). However, they are not easy to see, please represent them with a different color.

• Lines 377 – 380: The text is repeated.

• Lines 383 – 384: Please clarify the meaning of “The overall deformation trend was shown to deviate from the LOS direction.” Do you mean the point moved away from the SAR sensor?

• Lines 385 – 386: Please clarify the meaning of “… expansion phenomenon close to the LOS direction displacement appeared”. Do you mean the point moved towards the SAR sensor?

• Line 393: Please clarify the meaning of “deformation phenomenon away from the LOS direction”. Do you mean the point moved away from the SAR sensor?

• Figure 12e: I assume the figure shows the slope along a profile in area A. That profile should be represented on the three-dimensional model.

• Lines 421 – 423: The text is confusing, please clarify it. Please identify steps I, II, III, IV, V and VI in Figure 12(e).

• The captions from Figures 8 and 10 are equal – please correct.

• Figure 13: please add lines delimiting excavation and filling areas in the figure.

• Figure 14: why is the deformation in vertical direction instead of LOS, as in previous examples?

• Lines 455 – 456: it is not clear that points P5, 6 and 8 are the ones with deformation related to the rainy season and not P7. Please clarify the text.

• Lines 463 – 469: does the elevation along the section line refer to the situation before the excavation and filling works? That should be clear in the text.

• Line 511: It should be “trend away from the sensor”, instead of “trend away from the LOS direction.”

• Line 516: It should be “towards the sensor” instead of “close to the LOS direction”.

• Figure 16: The daily rainfall in the rainy season in 2021 is larger than in 2020; however, that does not result in a periodic deformation with larger amplitude. In the case of P1, the periodic deformation shows movement away from the sensor after the largest daily rainfall values, which is the opposite of the expected. Please comment.

Best regards.

Author Response

Dear reviewer:

We are very appreciate for your comments.We think these comments have helped us a lot in refining the manuscript and improving our research.The replies to each  comments are in the corresponding response( please see the attachment), and we marked the position of each reply in the tracking version.

Best regard

Authors

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Editor/Authors,

I have read the manuscript remotesensing-1669891 entitled “Surface deformation of expansive soil at Ankang airport, China revealed by InSAR observations”, and submitted for publishing to Remote Sensing Journal. The paper presents InSAR applications in a new airport location in Central China which has been constructed in a fragmented topography. The paper aims to describe the results in a much more proportion than to discuss it. This is my main concern about the value (otherwise the good work) of the manuscript, and its suitability for publishing. I would recommend to the authors to rewrite the discussion part, in order to assess the results by comparing to other similar papers (many of this part are in fact results), and to try to demonstrate the power of replicability of the method used.

Other technical (minor) suggestions in the *.pdf file attached.

Regards

Comments for author File: Comments.pdf

Author Response

Dear reviewer:

We greatly appreciate your opinion. We think these comments are of great help to us in refining the manuscript and improving the research. Replies to each comment are in the response file (see attachment), where we marked each comment's location in the tracked version.

Best regard

Authors

Author Response File: Author Response.docx

Reviewer 3 Report

Authors presented manuscript on ground deformations observed at Ankang airport, China using InSAR Sentinel data and combined with geology and climate records.

Why the foundation of the airport is built with the expansive soil material? We red that this is because of the characteristics of the geological body and authors explained that the foundation is concreted…But still this is quite risky, why foundation of the higher engineering properties (better bearing capacity, good stability, small uniform settlement) was not constructed, there? Difficulties with the carriage of such a big volume, probably….However the runaway is stable…

Authors should also provide E–W deformations in a future.

Is there any seismic risk in this area?

Manuscript is very interesting however must be reorganized and reordered, particularly it is noticed in section 5. Please provide reorganized manuscript.

Critical comments:

Line 28 – Authors mentioned about singular spectrum analysis as one of the method but did not presented an issue as a separate section, please reorganize manuscript.

Line 49 – Hazards are only potential, please correct.

75–76 –Please correct citations –Short et al. and 14 are the same.

Figure 1– Very small test area–too general figure. Please modify.

Figure 2 – Please provide full legend–we do not know numbers?

Lines 150–155 These statements are not clear and looks very similar, please clarify.

Table 1 – What DEM source was used, please provide details.

Figure 4 –Please better define the caption.

Line 293– There is no section 2.3. please reorganize manuscript.

Line 293–StamPS method is not described, please describe StamPS method. Please provide a correct section.

Figure 8 Please note that map is always spatial, figure 8 presents map of the PS velocity rate. (probably LOS–please clarify) or e.g. spatial PS distribution...

Lines 312–334 – These lines provide methods and data information (in this order?)–please reorganize manuscript.

Line 323–Please provide leveling data in data section.

Line 347– Please note that the figure 10 is placed in other chapter, so please reorganize manuscript.

Please note that the next section 5. must be reorganized. Authors show results.

Line 364–365 Please provide rainfall data in data section, please reorganize manuscript.

Figure 11– Caption is not clear, please order it ( where are A,B,C for instance?...)

Lines 377–423 The text body is messy, please correct and reorganize manuscript.

Figure 13– Please note that this is not a diagram, please correct. Not all map elements are included in the legend, please correct. Please also inform is LOS or vertical deformation presented.

Lines 443–469 This text body is not ordered: e.g. first presented figure 14, then 13 then 15, please reorder manuscript.

Lines 470–473 These two statements mean the same, please clarify.

Line 463– The morphological profile provided RR1 is not included in methodology section, please reorganize manuscript. Please inform about unit (m asl?)

Line 494–505 – Please shift to methodology section.

Figure 16 –Please provide an informative caption.

Lines 541–542 Please correct style.

Lines 553–563 Please correct style.

Line 549 –39 Sentinel-1 images were used? In section Dataset (line 158) authors wrote 40 Sentinel-1 images were used, this is not clear, please clarify.

Line 569–What means fragile foundation, please clarify.

General remark: Once author use PSI term another time PSinSAR, please clarify.

Author Response

Dear reviewer:

We greatly appreciate your opinion. We think these comments are of great help to us in refining the manuscript and improving the research. Replies to each comment are in the response file (see attachment), where we marked each comment's location in the tracked version.

Best regard

Authors

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear authors,

thank you for your answers. All questions have been properly addressed. There are only some language issues in the modifications performed in responses 8, 9, 10, 18 and 19, in which information is repeated. I suggest the following rephrasing:

• Response 8: "The overall deformation trend was away from the sensor"
• Response 9: "However, in the two rainy seasons, the deformation rate slowed down significantly, and an expansion phenomenon appeared, which was consistent with the soil mechanical properties of expansive soil to a certain extent"
• Response 10: "although the deformation phenomenon away from the SAR sensor also occurred in this area"
• Response 18: "showing an obvious settlement trend ."
• Response 19: "P1, P3, and P5 showed an obvious uplift phenomenon."

Best regards

Author Response

Dear reviewer:

We are very grateful for your comments and suggestions, We think these comments are of great help for us to be able to describe the results correctly. We have modified the language issues based on the your rewrite suggestions.

Best regards

Authors

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript was improved.

Author Response

Dear reviewer

We are very grateful for your comments and suggestions, We think these comments are of great help for us to improve our research. We have modified the language issues.

Best regard

Authors